package com.outfood.utils;

public class Distance
{

    private static final double EARTH_RADIUS = 6378137;
    private static double rad(double d)
    {
       return d * Math.PI / 180.0;
    }
   
    /**
     * 根据两点间经纬度坐标（double值），计算两点间距离，单位为米
     * @param lng1
     * @param lat1
     * @param lng2
     * @param lat2
     * @return
     */
    public static double GetDistance(double lng1, double lat1, double lng2, double lat2)
    {
       double radLat1 = rad(lat1);
       double radLat2 = rad(lat2);
       double a = radLat1 - radLat2;
       double b = rad(lng1) - rad(lng2);
       double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a/2),2) + 
        Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2)));
       s = s * EARTH_RADIUS;
       return s;
    }
   
   
    /**
     * @param args
     */
    public static void main(String[] args)
    {
    // TODO 自动生成方法存根
        double distance = GetDistance(121.491909,31.233234,121.411994,31.206134);
        System.out.println("Distance is:"+distance);
    }

}